Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

623
FXUS63 KLOT 102346 CCA
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
601 PM CDT Fri Jul 10 2026...CORRECTED

.KEY MESSAGES...

- Chances for showers and storms persist into this evening
  south of I-80.

- Drier and warmer conditions are expected into early next with
  cooler conditions near Lake Michigan.

&&

.DISCUSSION...
Issued at 237 PM CDT Fri Jul 10 2026

Early this afternoon, a surface frontal boundary remains draped
from west-to-east across my southern CWA from southern Lasalle
county through Newton and Jasper counties in IN. Diurnal heating
of the very moist low-level airmass (surface dew points in the
low to mid 70s) through the morning has eroded convective
inhibition, resulting in isolated shower and thunderstorm
development along and near the boundary. This activity is
expected to persist on a widely scattered basis this afternoon
into this evening, particularly south to well south of I-80.
Severe weather is not anticipated with these storms, owing to
the poor deep layer shear. However, some locally gusty winds up
to 40 mph will be possible with the strongest cells. Also,
cannot 100% rule out the possibility for a brief landspout type
tornado with the convection right along the the surface
boundary. Otherwise, the slow eastward motion of 10-15 mph will
result in some locally heavy rainfall.

The surface frontal boundary will sag southward into downstate
IL tonight and on Saturday as a slow moving convectively
enhanced mid-level impulse shifts east-southeastward from the
Mid-Missouri Valley out across the Mid-Mississippi Valley. This
track is expected to push the primarily focus for showers and
thunderstorms on Saturday south of our area. Accordingly, our
current forecast thus only mentions a low (20%) chance for areas
as far north as around the U.S. 24 corridor. Elsewhere, partly
cloudy skies are expected, with inland temperatures topping out
in the mid 80s. Cooler conditions (mid to upper 70s) are again
anticipated along the Lake Michigan shore, owing to the
persistent onshore northeasterly winds.

Temperatures will begin to warm Sunday back into the upper 80s
(mainly inland locations) on Sunday in response to the building
of a large and anomalous mid/upper- level ridge. This upper-
level ridge/high is forecast to peak in amplitude Monday into
Tuesday, when 500 mb heights peak around 600 DAM across the
Dakotas. For reference, this is nearly 3 standard deviations
from normal! Across our area high temperatures are expected to
be into the low 90s, particularly inland from the lake. Closer
to the lake, the potential for daily lake breeze development
through the week suggests that cooler afternoon conditions (80s)
will result. Fortunately, the hot inland temperatures do not
look to be accompanied by significantly high dewpoints/RH.
Accordingly, peak afternoon heat indices next week do not look
to get out of the 90s.

Our rain and storm chances look to remain rather minimal Sunday
through at least early next week as this large expansive ridge
dominates across the northern Plains into the Upper Midwest.
However, later next week (Thursday into Friday) there are signs
in the ensemble guidance that an anomalous trough/low digging
into eastern Canada will flatten the ridge across the Great
Lakes region. As this occurs, our area may become better
positioned for experiencing more episodes of showers and
thunderstorms later next week.

KJB

&&

.AVIATION /00Z TAFS THROUGH 06Z SUNDAY/...
Issued at 601 PM CDT Fri Jul 10 2026

With a surface high pressure system expected to remain parked
along the Ontario and Quebec borders tonight and tomorrow,
generally northeasterly winds will prevail at all terminals
through the TAF period. Will be watching to see if winds at ORD/MDW
slip north to even northwesterly overnight, though speeds would be
less than 5 kt should that occur and turn back northeasterly after
daybreak. Broken high clouds will prevail.


Borchardt

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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